Comparison of Bacterial Microleakage of Endoseal MTA Sealer and Pro-Root MTA in Root Perforation

Statement of the Problem: Different materials have been used to repair root perforations, the most successful of which is mineral trioxide aggregate (MTA). It is technically difficult to use MTA for perforation repair. Recently, some bio-ceramic sealers such as Endoseal MTA were introduced to repair the perforation site during root filling, which decreases the technical difficulty of this procedure. Purpose: The aim of this study was to compare the bacterial microleakage of Pro-Root MTA and Endoseal MTA sealer in root perforation repair. Materials and Method: This in vitro experimental study evaluated 40 extracted canine teeth. After root canal cleaning and shaping, a root perforation was artificially created at 7 mm below the cementoenamel junction. The teeth were then randomly divided into two experimental groups (n=18) of Pro-Root MTA and Endoseal MTA, and two positive and negative control groups (n=2). Perforation sealing and root canal filling were performed in the two experimental groups according to the manufacturers’ instructions. After sterilization of the whole system with gamma ray, microleakage was tested using a double-chamber model. Data regarding the presence/absence of microleakage were reported after 35 days. The data were analyzed by SPSS software using the Chi-square test. Results: There was no significant difference between the two experimental groups regarding bacterial microleakage (p> 0.05). Conclusion: Under the conditions of this study, it can be concluded that the sealing ability of perforation repair with Endoseal MTA Sealer and Pro-Root MTA was comparable.


Introduction
Root perforation is a procedural error that may occur during root canal treatment. Although deep caries or resorptive processes may also cause perforations, most root perforations occur iatrogenically. Root perforations resulting in endodontic treatment failure account for approximately 10% of all failed cases [1].
Root perforation refers to a communication between the root canal system and the external root surface [2].
Root perforation affects the long-term prognosis of the tooth. The prognosis of endodontic treatment of such teeth depends on the size, position, and time of perfora-tion, as well as the sealing ability of the material used for perforation repair [3]. The prognosis would be relatively good if the perforation is quickly detected and sealed with a biocompatible material [4]. Various materials have been used to repair the perforation site. An ideal restorative material to repair radicular perforations should be non-toxic, nonabsorbable, radiopaque, and bactericidal or bacteriostatic, and should provide a hermetic seal against microleakage [5]. Mineral trioxide aggregate (MTA) was introduced to endodontics in to seal the communications between the tooth and the external root surface [6][7]. In addition to being used in root end filling, it is also widely used in other cases such as vital pulp therapy, pulp revascularization, and root perforation repair [7][8][9]. Assessment of physical, chemical, and biological properties of MTA confirmed its efficacy as a suitable material to seal root perforations [7,[10][11]. Despite the optimal sealing ability and other advantages, long setting time and difficult handling are the main drawbacks of MTA for use in root perforation repair [9,12]. Recently, Endoseal MTA (Maruchi; Wonju, Korea) was introduced to the market, which is an injectable calcium silicate-based root canal sealer.
Endoseal MTA has favorable biocompatibility/ odontogenicity comparable to AH Plus (Dentsply DeTrey, Germany), which is a widely used resin-based sealer [13]. The manufacturer claims that it has high sealing ability; on the other hand, its clinical application is easier than that of conventional MTA for root perforation repair. Considering the limited number of studies on sealing ability of Endoseal MTA, the aim of this study was to evaluate and compare the bacterial microleakage and sealing ability of Endoseal MTA and Pro Root MTA in root perforation repair.

Preparation of teeth and perforation repair
The study was conducted at the Department of Endo- In the group B, the perforation was repaired with Endoseal MTA sealer, and the canals were filled according to the manufacturer's instructions. The teeth were then incubated for 24 hours similar to group A.
In the group C, samples served as the positive contr-ol, which received no restorative material at the perforation site or in the root canal. The next steps were carried out as in other groups.
In the group D, samples served as the negative control with no perforation. The entire access cavity was filled with sticky wax (Pyrax, India). The next steps were carried out as in other groups.
The groups were coded such that the examiner was blinded to the type of treatment and the material used for perforation repair. The teeth were then sealed with composite resin (2 mm at the root end) to prevent microleakage through the apex. The entire root surface, except for the perforation site and 1mm margin around the perforation site, was coated with two layers of nail varnish (Isadora, Sweden) to prevent bacterial microleakage through the dentinal tubules and accessory canals ( Figure 1). In the positive control group, nail varnish and composite application was performed as in groups A and B, except that the access cavity was directly connected to the outer root surf-ace via the perforation. In the negative control group, the entire root surface was covered with two layers of nail varnish and the access cavity was filled with sticky wax.

Bacterial microleakage test
A double-chamber system was designed and used to evaluate bacterial infiltration. Specimens were examined over a period of 35 days, during which the teeth were kept in an incubator and checked daily. The turbidity of the culture medium indicated bacterial microleakage. At the end of the experiment, the bile esculin combined with 6.5% NaCl tolerance test was performed to confirm the bacterial infiltration in case of culture medium turbidity [11][12][13][14][15]. Assessments were made by a person blinded to the type of sealing material used. Data were analyzed using SPSS version 19 via the Chi-square test. All statistical tests were performed at the significance level of the p 0.05. Table 1 present the bacterial microleakage data in the experimental groups. In Endoseal MTA group, no bacterial microleakage was noted after 35 days. In Pro-Root MTA group, three (17%) samples showed bacterial mic- However, the Chi-square test revealed no significant difference between the two experimental groups (p> 0.05). Bacterial microleakage was observed in all positive control teeth 24 hours after the onset of the experiment. However, bacterial microleakage did not occur in any of the negative control teeth (Figure 3). The results of bile esculin combined with 6.5% NaCl tolerance test as well as Gram staining confirmed the microleakage of E. faecalis into the culture media that showed turbidity ( Figure 4).

Discussion
Different materials have been used to repair root perforrations [14]. MTA is the most commonly used material for root perforation repair [15]. However, it is technically difficult to use MTA for perforation repair.   injected into the root canal system. It is self-cure and gradually sets when exposed to air by absorbing the ambient moisture without requiring any mixing. According to the manufacturer, this calcium-silicate cement can be considered as a MTA-derived material because its chemical composition resembles that of MTA.
Therefore, it is expected to have favorable physical and biological properties similar to other MTA-derived materials reported in previous studies [16][17][18]. Furthermore, this injection-type, self-setting root canal sealer has a user-friendly application, which is a clinical advantage [13]. According to the manufacturer, this sealer can be used to seal root perforations. Therefore, in this study, we compared the perforation sealing ability of this sealer with Pro-Root MTA, which is the most acceptable material for perforation seal. Bacterial microleakage is the cause of most endodontic infections, so in this study microleakage test was performed using the bacterial infiltration technique. In this study, we used E.
faecalis because it seems to play a significant role in the etiology of persistent periradicular lesions [19]. It should be noted that bacterial microleakage test, although is more similar to clinical conditions than other methods such as dye penetration test [20], it has limitations when evaluating the sealing ability of materials which have antibacterial properties such as Pro-Root MTA and Endoseal MTA that were used in this study.
In this study, we evaluated microleakage over a period of 35 days; in other studies, periods of 30 days or more were used [6,[21][22]. Further studies are required to better elucidate this topic.